Wire printer



J1me 1959 F. J. FURMAN EI'AL 2,889,770

WIRE PRINTER Filed Dec. 30. 1954 6655656! 0000000 oooooool oooooool 00000 10 JNVENTORS FRANK J FUR MAN ROBERT V SIMPSON FIG.5

ATTORNEY WIRE PRINTER Frank J. Furman, Endicott, Owego, N.Y., assign'orsto chines Corporation, of New York Application December 30, 1954, SerialNo. 478,649 Claims. (Cl. 10193) and Robert V. Simpson, InternationalBusiness Ma- New York, N.Y., a corporation This invention relates towire printers and more particularly to print head assemblies wherein theprint ends of a plurality of print wires, through their guide tubes, aregathered together into a character printing cluster and moved toward andaway from recording material so as to undergo printing impact in what isoften called front printing. (See, for example, the United States patentapplication Ser. No. 384,697 of Reynold B. Johnson, filed October 7,1953, now U. S. Patent No. 2,785,627.

In previously constructed print head assemblies for wire printers, theprint heads have been formed with a cavity designed to more or lessexactly receive the closely dimensioned ends of the guide tubes for therespective print wires, usually thirty-five in number and arranged in apattern of seven columns and five rows. The closely dimensioned size ofthe cavity enabled the tubes to be clamped in the print head to define afixed pattern and be movable therewith.

In a print head assembly constructed as above described, it will beapparent that each tube and, hence, its corresponding print wire tookits position from the adjacent tube. Any variation in the outsidediameter of a tube would result in a row and/or column of tubes whichwere misaligned with the rest, and this misalignment would in turn bereflected in misalignment of the corresponding print wires. Thismisalignment would be over and above that which might obtain as a resultof play permitted by a variation in the internal diameter of a tube,which, while not affecting the location of the other tubes and printwires, might allow the instant print Wire to print out of alignment withthe remainder of the print wires. In addition to the possiblemisalignment of some print Wires with the remainder thereof, if theoutside diameter of the tubes was smaller than the normal size, theassociated print wires in the corresponding rows and columns would bespread over a smaller distance, with the result that characters ofreduced size would be printed. It can be seen that it is comparativelydifiicult and time-consuming, if not impossible, to provide print headassemblies of the conventional construction wherein the print wires-areuniformly spaced and whereby characters of perfect size and alignmentmight be obtained.

Wire printing has become increasingly important because of its readyadaptability to high speed operations. In many applications, forexample, business papers, it is desirable to have printed characters ofhigh quality. Such quality is to a considerable extent dependent on theproper alignment of the component dots of the characters, particularlyin their vertical and horizontal bars as in the letters E and T.

Progress has also been made in mechanisms for sensing printedcharacters, and according to at least one scheme, the presence orabsence of a particular character is determined by sensing for thepresence or absence of marks at just a few points in the total characterpattern; the code being such that no other character would be comprisedof markings at similar points. It can be seen that characters formed ofa pattern of dots particularly lend atent Ofiice 2,889,770 Patented June9, 1959 themselves to character sensing. On the other hand, it can alsobe appreciated that each component dot of a character must appear in itsproper place; if it should be out of alignment, its presence might notbe detected and a different character may be read.

Accordingly, it is the principal object of this invention to provide aneasily constructed print head assembly having substantialy uniformlyspaced print wires capable of producing characters of substantiallyperfect size and component dot alignment.

Another object of the invention is to provide a print head assembly thatis adapted to high speed printers and reliable in operation.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of examples, the principle of the invention andthe best mode which has been contemplated of applying that principle.

In the drawings:

Fig. 1 is a longitudinal vertical section through an embodiment of theinvention.

Fig. 2 is a plan view of the embodiment shown in Fig. 1.

Fig. 3 is a right-hand end view of the embodiment shownin Fig. 1.

Fig. 4 is a disassembled in Fig. 1.

Fig. 5 is a bottom view Fig. 4.

Fig. 6 is an enlarged end view of the print head shown in Fig. 4.

In accordance with the invention, the print head, generally indicated bythe numeral 10, is formed of molded nylon or like material and with acavity 12 (Figs. 4 and 5) on its underside. The front end of the printhead is formed with a vertical wall or plate 14 which serves to limitthe front end of the cavity. In this front wall there are formed aplurality of apertures 16 (Fig. 6) through which print wires 18 areslidably accommodated, and it is a feature of this invention that, byaccurately locating the apertures 16 in the wall 14, the print wires 18may be held in substantially perfect aligned relationship and perfectspread.

According to a preferred scheme, the apertures 16 are drilled in thewall 14 by means of a pantograph machine. Normally, the characterpattern is selected from a group of thirty-five Wires arranged in fivecolumns of seven wires each, and accordingly, a template is preparedhaving thirty-five holes drilled on center distances a number of times,for example, ten, the center distances which view of the print headshown of the print head shown in are to obtain between the various pn'ntwires. After a template has been prepared, as set forth, it is insertedin the pantograph machine which, in turn, drills the apertures in thefront Wall 14 at one-tenth the distances between the holes in thetemplate. It will be evident that this reduction cuts the originaltolerances by one-tenth and enables the print wires to be located with aminimum of variation on center distances so that characters of uniformsize and perfect alignment of the component dots are readily obtained.The formation of the head of nylon or like material facilitates theaccurate location and drilling of the relatively frictionless and Wearresistant apertures therein.

Once the apertures have been drilled in the print head front wall, theyare used to locate the respective print wn'es 18 in the print head, andWhereas formerly the guide tubes 20 were used to locate the print wiresin the print head, the print Wires are now used to locate thecorresponding guide tubes therein. In carrying out this construction,the print wires are inserted in successive columns of the apertures 16drilled in the front wall 14, preferably beginning at one side of theprint head and working thereacross in order. After each column of printwires has been inserted into the corresponding apertures, thecorresponding guide tubes 20 for the wires are mounted thereon.

Conveniently, the tubes for eachcolumn of print wires are solderedtogether as an aligned unit before they are placed on the correspondingprint wires. Since it is desirable to have the ends of the respectivetubes adjacent the inner surface of the print head front wall 14 so asto prevent buckling in a wire extending between the end of the tube andits :front wall aperture, the tubes are all joined together so thattheir common ends terminate along a common line. However, since the endsof the tubes are to be located by the print wires extending through thefront wall apertures, it is necessary to solder the tubes together atpoints slightly removed from their aligned ends.

After the print Wires have been inserted into a column of apertures 16,they are inserted one by one into the corresponding tubes 20, andthereafter the tube unit is slidably moved upon the wires until theircommon ends abut against the print head front wall. This operation isrepeated for each of the other columns of apertures in the print headfront wall until all of the tube units have been assembled into theprint head.

In this condition, while the tubes are not secured to the print head formovement therewith nor to the tubes of the adjacent units, they are allaccurately located in the print head so that their channels are alignedwith the apertures in the front wall. A single unitary structure isformed of these components by using a cement, such as those made by DuPont, Minnesota Mining Co., or (JD-300, as a bonding material.Thereafter, when the print head is made to undergo a printing stroke, itcarries with it the guide tubes 16 so that any print wires which havebeen differentially preset to project from the face of the wall 14 aremade to undergo printing impact with a recording material.

It will be evident then that, in addition to providing a print headassembly capable of printing characters of substantially uniform sizeand perfect aligment, there has been provided an assembly which isexceedingly simple and easy of construction. Only a few parts arerequired, and these do not require close tolerances save for oneelement, and in these the standard can be readily obtained. The guidetubes may be of smaller external diameter than formerly employed, withthe result that the external diameter is no longer critical. The cavity12 in the print head also does not have to be closely dimensioned asbefore. Moreover, the use of the cement eliminates the need for extramaterial as was formerly required to secure the tubes in place and tothe print head. It will be obvious that there has also been provided aprint head assembly of relatively light weight.

The lightweight yet rugged construction of the print head assembly isparticularly adapted'to high-speed printers. The low mass enables ofrapid acceleration so that high impact velocities may be quicklyobtained. This results in a reduction of the possibility of breakage inthe drive wire for the print head assembly and, in fact, enables drivewires of lighter construction than heretofore employed, thus furtherreducing the mass which must be operated and materially reducing theenergy expenditures as Well as the noise of high-speed printers.

Moreover, the use of a lightweight material for the print head, such asnylon, in a lightweight print head assembly makes feasible thelengthening of the print head so that it extends behind the exit for theprint wire guide tubes. This enables the drive wire 22 (Figs. land 2)for a print head to be attached to the print head generally in line withthe center of mass thereof, thereby reducing the possibility of a couplebeing formed between the print head and the means which slidablyaccommodates its movement. Not only does this result in smootheroperation of the print head assembly, but

there also obtains a more uniform character impression as well as afurther reduction in the possibility for breakage of the assembly drivewire.

This extended print head feature finds particular use in the wireprinter mechanism disclosed in the US. Patent application of Furman,Moneagle, and Simpson, filed on even date and bearing Serial No.478,650. In this patent application the guide tubes and print wirestherein are shown as being formed with a second curve which materiallyreduces the mass which is shifted when the print head assembly undergoesa printing stroke. As constructed, the instant print head enables aportion of the second curve to be accommodated within the print head 10,thereby facilitating attachment of the drive wire 22 to the print headin line with its center of mass. Viewing Fig. 1, it may be seen that theprint head 10 is of such length that the guide curved tubes 24) pass outof the cavity 12 and lie beneath the rear end of it. The shape of therear end of the cavity conforms generally to the curves in the tubes.The cavity terminates short of =the rear end of the print head which isformed with a vertical opening 24. A slot 26 connects the lower end ofthe opening 24 with the rear end of the print head.

Connection of the print head to the drive wire is made through theopening 24-and slot 26. The end of the drive wire 22 is threaded, and onthis thread are screwed two nuts 28 and 30. The nuts are left spacedfrom each other so that the drive wire portion therebetween may bereceived in the slot 26 in the rear end of the print head While the nut36 is received in the hole 24. Thereafter, the :nuts 28 and 30 arescrewed toward each other to lock the printhead'to the drive wire.

In Figs. 2 and 3 a pair of print heads is shown. Each print head 10 maybe mounted in a corresponding groove 31 formed in the upper side of atransversely extending bar 32 and as being confined in this groove forendwise movement only by a plate 34 removably fixed to the top of thebar 32. The properties of nylon and steel are such that relativelylittle friction occurs between these relatively moving parts, thusminimizing wear and tear as well as lubrication problems. Moreimportantly, it produces no material load on the drive wires 22 for therespective print head assemblies, thereby further enhancing high-speedoperation of the printer.

The drive wires 22 for a pair of print heads 10 are mounted incorresponding tubes 36 which confine them against buckling when a thrustis imparted to them to move the print head through a printing stroke.The forward ends of the pair of tubes are secured, as by soldering, inslots 38, formed in the upper surface of a block 40. The block iscarried on the rear end of a bracket 42 fixed at its forward end to theunderside of the bar 32 so as to lie between the tubes 20 for therespective print heads.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in theart, without departing from the spirit of the invention. It is theintention, therefore, to be limited only as indicated by the scope ofthe following claims.

What is claimed is:

1. In a print head assembly for high-speed wire printers having printwires mounted in curved, flexible guide tubes movable at their one endsto carry projecting print wires into engagement with print receivingmaterial on a platen, a movable print head having at one end a plateformed with a plurality of apertures respectively accommodating saidprint wires and mounted so that the plate faces the platen, means fixingthe one ends of the guide tubes in said print head so that the openingsthereof are aligned with the apertures for the corresponding print wireswhich extend therein, and actuating means for moving the print headtoward and away from the platen to cause projecting print wires toundergo a print stroke through the action of the print head carrying theone ends of the guide tubes which in turn carry the print wires.

2. In a print head assembly for high-speed wire printers having printwires mounted in curved, flexible guide tubes movable at their one ends-to carry projecting print wires into engagement with print receivingmaterial on a platen, a movable print head having at one end a plateformed with a plurality of apertures respectively accommodating saidprint wires and mounted so that the plate faces the platen, means fixingthe one ends of the guide tubes in the print head so that the endsthereof are disposed adjacent said plate and the openings thereofaligned with the apertures for the corresponding print wires whichextend therein, and actuating means for moving the print head toward andaway from the platen to cause projecting print Wires to undergo a printstroke through the action of the print head carrying the one ends of theguide tubes which in turn carry the print wires.

3. In a print head assembly for high-speed wire printers having printwires mounted in curved, flexible guide tubes movable at their one endsto carry projecting print wires into engagement with print receivingmaterial on a platen, a movable print head formed at one end withapertures spaced on center distances equal to the desired centerdistances between the component dots of a character pattern andrespectively mounting the printing ends of said print wires, meansfixing the one ends of the guide tubes in said head so that the openingsthereof are disposed in line with the apertures for the correspondingprint wires, and actuating means for moving the print head toward andaway from the platen to cause projecting print wires to undergo a printstroke through the action of the print head carrying the one ends of theguide tubes which in turn carry the print Wires.

4. In a print head assembly for high-speed wire printers having printwires mounted in curved, flexible guide tubes movable at their one endsto carry projecting print wires into engagement with print receivingmaterial on a platen, a movable print head formed at one end withapertures arranged in columns and rows on center distances equal to thedesired center distances between the component dots of a characterpattern and respectively accommodating the printing ends of said printwires, means fixing the one ends of the guide tubes in said head so thatthe openings thereof are disposed in line with the apertures for thecorresponding print wires which extend therein, and actuating means formoving the print head toward and away from the platen to causeprojecting print wires to undergo a print stroke through the action ofthe print head carrying the one ends of the guide tubes which in turncarry the print wires.

5. In a print head assembly for high-speed wire printers having printwires mounted in curved, flexible guide tubes movable at their one endsto carry projecting print wires into engagement with print receivingmaterial on a platen, a movable print head having an end wall formedwith a plurality of apertures respectively accommodating the printingends of said print wires, a bonding agent securing the one ends of theguide tubes to each other and said print head and so that their openingsare aligned with the apertures for the corresponding print wires whichextend therein, and actuating means for moving the print head toward andaway from the platen to cause projecting print wires to undergo a printstroke through the action of the print head carrying the one ends of theguide tubes which in turn carry the print wires.

References Cited in the file of this patent

